Theoretical and Experimental Analyses of Heat Transfer in a Flat-Plate Solar Collector

In this paper, the heat transfer in a flat-plate solar collector with water tubes spreading across its width was analyzed. The performances of the system both theoretically and experimentally were evaluated and compared. The theoretical results obtained agreed well with the experimental results, except that a slight higher deviation of heat loss was obtained in the experimental analysis and low solar radiation in the morning and late afternoon affects the system. An average heat loss coefficient of 0.68 W/m2.°C was obtained in the experimental analysis, while 0.65 W/m2.°C was obtained in the theoretical analysis. The collector efficiency was high around the mid-day when the collector receives the highest energy and the useful heat rate was at its maximum. The results also reveal that the performance of the solar collector depends much on the heat rate. The collector efficiency increases as the heat rate increases until a maximum efficiency of 72.2 % was reached at optimum heat rate of 785 W.